﻿abstract class Game
{
    public void Play()
    {
        Console.WriteLine(Start());
        Console.WriteLine(End());
    }

    public abstract string Start();
    public abstract string End();
}

class Tetris : Game
{
    public override string Start() => "开始俄罗斯方块";
    public override string End() => "结束俄罗斯方块";
}

abstract class fuck
{ 

}



void PlayGame(Game game)
{
    game.Play();
}

PlayGame(new Tetris());